1. Field of the Invention
This invention relates generally to pipe clamping devices, more particularly, to an articulated pipe jack clamp having a pair of L-shaped leg members hingedly connected at an upper end to a central threaded collar in laterally opposed relation and having inwardly turned bottom ends engageable with a pipe jack cradle and an inverted V-shaped head at the end of a threaded stem that securely clamps a work piece or pipe into the pipe jack cradle.
2. Brief Description of the Prior Art
Welders, pipe fitters, and fabricators often use a pipe jack for welding or fabricating work pieces, particularly pipe of various diameters. The pipe jack has a wide V-shaped cradle with a threaded shaft received in a tubular base. The height of the V-shaped cradle is adjustably raised or lowered by turning a hand crank nut threadedly engaged on the shaft and rotatably supported on the base. The work piece or pipe is supported in the V-shaped cradle. Some methods of welding pipe involve placing the pipe on a jackstand and tack welding the pipe to the stand. After the fitting has been tacked to pipe, the pipe must be separated from the stand. Thereafter, tacks securing pipe in jackstand must be removed from the pipe. This is a cumbersome and time-consuming operation. In other methods, clamping devices are often used to secure the work piece or pipe to the pipe jack in order to prevent movement and prevent injuries.
There are several patents that disclose various devices capable of clamping or securing work pieces such as pipes. Some of these devices are fairly complex employing a number of moving parts, which could make them cost prohibitive. Also, some of these are of unitary construction and would require several devices to fit a wide range of pipe diameters. Others are not suitable for use with a pipe jack.
Robinson, U.S. Pat. No. 2,108,077 discloses a pipe joint welding clamp consisting of a V-shaped angle iron with two longitudinally spaced hinge bosses on one side, and two yokes, each of unitary construction having an arcuate top portion with a threaded opening therethrough, and integral opposed side portions extending downwardly therefrom. The bottom portion of one side is inwardly turned to engage the underside of the angle iron, and the bottom portion of the opposed side is rotatably mounted in the hinge boss on the side of the angle iron. This device is not particularly suited for use with a pipe jack, and does not have hinged side portions.
Wietrzyk, U.S. Pat. No. 4,139,189 discloses a clamp of unitary construction having an arcuate top portion with a threaded opening therethrough, and integral opposed side portions extending downwardly therefrom with inwardly turned bottom ends that engage slots on two opposing sides of a conventional V block. The device is used with a conventional V block and a pair of V block centers to support and center any rectangular stock upon the V block, while being machined.
Peterson, U.S. Pat. No. 4,195,828 discloses a boiler tube clamp comprising a U-shaped bracket having spaced free ends and a curved intermediate portion for nestingly receiving a tube end portion. An elongate pin is removably connected to the free ends for caging the pipe end portion therebetween. An adjustable threaded positioning member carried by an offset portion of the clamp moves an adjacent tube section into alignment with the tube section caged in the clamp.
Kubo, U.S. Pat. No. 4,524,959 discloses a holder for use in holding two pipes or pipe joints to be welded where one of the pipes or pipe joints is held by three pipe abutting members mounted in angularly spaced relation on a common holder with the position of the pipe abutting members being adjustable by a screw bar. The other pipe or pipe joint is held by means of three supporting screw bars adjustably mounted in the pipe abutting members.
Penny, U.S. Pat. No. 5,135,209 discloses a pipe clamp apparatus similar to a C-clamp having opposed V-shaped brackets for clamping a pipe therebetween.
Howell, U.S. Pat. No. 5,863,035 discloses a pipe jack clamp comprising a yoke of unitary construction having a top cross member with a threaded opening therethrough, a pair of side members fixed thereto extending at an obtuse outward angle downwardly therefrom terminating in an inwardly turned distal end extending at a right angle therefrom, and a threaded stem threadedly engaged in the threaded opening having a handle at the top end and an inverted V-shaped head rotatably mounted at the bottom distal end. Unlike the present invention, the side members are not articulated or pivoted, the pipe contact surfaces are not rubber coated, the head is not connected with a ball and socket connection, and because the side member are fixed, Howell requires that the clamp be slid over one end of the pipe and the V-shaped pipe jack support element.
McBee, U.S. Pat. No. 6,349,869 discloses a welding clamp which attaches along its base portion to the receiving plate of a conventional jack stand. An upright member extends from the base and is angled in a direction which extends toward a vertical axis defined by the jack stand. The support member provides a sleeve for receiving in an adjustable horizontal arm. One end of the arm defines a threaded aperture through which a bolt is positioned. The bolt is used to secure a segment of pipe within the pipe stand without a need for temporary tacking welds between the pipe and the jack stand.
The present invention is distinguished over the prior art in general, and these patents in particular by articulated pipe jack clamps that include a pair of L-shaped leg members hingedly connected at an upper end to a central threaded collar in laterally opposed relation, each having an elongate upper portion extending downwardly from the collar and terminating in a shorter inwardly turned bottom portion engageable with the underside of a wide V-shaped cradle of a pipe jack. A threaded stem threadedly engaged in the collar has a handle at its top end and an inverted V-shaped head, preferably rubber coated, connected at its bottom end by a ball-and-socket connection. In an alternate embodiment, the inward facing bottom portion of one leg is hinged to its upper portion and is fixed to the pipe jack cradle, such that entire clamp assembly pivots to one side of the pipe jack.
The work piece or pipe is preferably supported on rubber pads in the wide V-shaped cradle of the pipe jack, the clamp is placed vertically downward over the pipe such that the inverted V-shaped head is engaged on the top of the work piece or pipe, and the inwardly turned bottom portion of each leg is disposed beneath the outwardly diverging sides of the V-shaped cradle, then the V-shaped head is screwed down to raise and engage the bottom portion of the legs on the underside of the V-shaped cradle, thereby securely clamping the work piece or pipe to the pipe jack.